Posted
by
Hemos
on Monday November 20, 2006 @09:01AM
from the understanding-how-we-are dept.

eldavojohn writes "Pending your beliefs about evolution, National Geographic is running an interesting article on the influences of behavior on evolution. The study supports the controversial idea that an animal's behavior in response to environmental change can spur evolutionary adaptations. By adding a predator to an island where a species of lizards lived with no predators, they witnessed a quick shift in the average length of legs on the lizards. Long legs meant to escape were useless against the new larger predators while short legs became the dominant feature since they increased climbing ability (to trees the predators could not reach). For the finer details on the research, visit the Losos Lab Research Page."

I'm hijacking a higher thread since pretty much everything written below is just plain wrong.
Not the submitters' fault, they simply read the article and based what they wrote on it.

Let me explain:
The article is claiming that "Evolution's Driving Force Shifts Based on Behavior"
Go to the actual research site (linked in submission), scroll down to the end, and you will find that what they're saying is:
"... another alternative is that lizards growing in different environments grow different length legs. To test this hypothesis, we raised baby anoles on two different surfaces at the St. Louis Zoo--either on 2x4's or on narrow (1/4") dowels. At the end of three months, the lizards raised on broader surfaces had longer limbs than the lizards on narrower surfaces! This suggests that the results observed in the field may be the result of a phenotypic plasticity in limb growth, rather than genetic differentiation."

Phenotypic plasticity [wikipedia.org] is a term some of you may be unfamiliar with, a good example of it is found in ants.

In any given hill, there are different castes of ants. Warriors, workers, etc. They are all quite different.
However, the differences are not genetic; they arise during development and depend on the manner of treatment of the eggs by the queen and the workers, who manipulate such factors as embryonic diet and incubation temperature. The genome of each individual contains all the instructions needed to develop into any one of several 'morphs', but only the genes that form part of one developmental program are activated.

This is what the study suggests is happening to these lizards.
They're saying there are at least two different 'morphs', one with long legs and one with short ones, in the genome of the lizards.
These are then selected between (through some so far unknown mechanism) based on the environment of the lizards.

"These findings suggest the intriguing possibility that phenotypic plasticity may play an important role in adaptive differentiation by permitting lizards to occupy different habitats; once subsequent mutations arise, these differences can then be elaborated upon by natural selection."

Now, let the ghosts of Lamarckism [wikipedia.org] the article has raised from their graves go to rest.

If phenotypic plasticity could affect the development of sperm cells, would it provide a plausible mechanism for Lamarckian evolution? For example, could environmental factors affect the concentration of proteins that might influence the crossover process during meiosis? Might this explain why sperm are produced continuously rather than being produced before birth and stored, like eggs?

Interesting thought, but no.
Phenotypic plasticity can only select between states already present in the genome. Activating a certain subset of genes, but not altering the genome as is required in Lamarckian evolution. (Lamarckian evolution in a nutshell is generations of giraffes stretching their necks to reach the higher leaves, passing the added length they train through life on to their decendants)

What could (as far as I understand) be theoretically possible, is for males to "select" the sperm to produce from a set of phenotypes. Perhaps dependent on hormonal activity, etc. (Producing "warrior children" if they had been stressed, angry and afraid over a long period of time?)
Don't really know if it's possible, but it would give a distinct survivability advantage to be able to "devolve" the next generation back to an earlier phenotype if conditions were too harsh...

You may be overly trusting in the article writer. The writer may have deliberately misinterpreted the article so as to create a controversy, base on the study's title. The idea that behavior doesn't influence evolution would actually be a whole lot more controversial among people who understand the subject.
You could post exactly the same information, put a headline to the effect that it supports 'intelligent design theory,' and watch the outraged comments pile up! What fun!

I've mentioned this before in a similar article months ago. There are studies of twins separated at birth, either raised at sea level or high in the Andes. Even though the two individuals are genetically identical the ones raised in the mountains are barrel chested and stout whereas the siblings raised at sea-level are average. Plasticity due to behavior (needing to breath deeply in a thin atmosphere - perhaps not voluntary but still a behavior), caused a person to develop differently.
Link to one artic

You misunderstand.
I'm not questioning evolution, I'm defending it. Reread what I wrote.
The article (at least the title, and the rest was way easy to (mis)understand that way) and the summary here was attacking evolution as we know it.

And that also is a question about the studies done here - is this evolution, or adaptation? Some make a distinction between the two, others think that adaptation is evolution at a micro-scale.I personally believe it's more adaptation and survival of the fittest. I akin it to races among humans - darker skin of African or Middle Eastern people is an adaptation to the environment, but not specieation or evolution. Genetically, race != species, but the differences between all races of people are obvious ada

It's not a knock for or against evolution, just a thought that people too quickly label "evolution" that which is simply stronger traits surviving under different conditions.

Huh? You're making a distinction that doesn't exist. Evolution is the change of the frequencies of alleles within a population over time do to differential reproductive success of individuals. There are a lot of reasons for this differential reproductive success, but two biggies are being alive to reproduce (you didn't get eaten

It's controversial because someone had the audacity to says that these changes aren't due to some sort of "higher power" (God, Muhammad, whatever deity you happen to believe in). Therefore some right wing nutjob group will likely have a hissy fit over this.

Right wingers can't be religious people. They can only assert they are (and they probably know it since they kill religion the same way fascism kills nationalism) but reading the ABC of most religions proves the opposite.

This discovery seems to me more "dangerous" for current science theories than current religions. It implies that will could have a different meaning than the mere transition of electrons in some areas of the brain. Down with Darwin, go Lamarck:D

It disproves the higher power Direct intervention in reality, sure. But didn't the predominance of an OS like windows have the same effect, or stronger? Anyway I didn't believe in it already, even if I believe in the possibility of a higher power being responsible for reality. If you think about it, imperfect creatures created by the higher power are much more problematic for theology than a higher power creating the universe, giving freedom to everything inside.

This discovery seems to me more "dangerous" for current science theories than current religions. It implies that will could have a different meaning than the mere transition of electrons in some areas of the brain. Down with Darwin, go Lamarck:D

So what are you suggesting? That "will" is somehow changing the DNA? Of course it isn't. This in no threat to Darwinism. All that is happening is that the lizards are moving into a situation where shorter legs are more favoured, so those with shorter legs are mo

Then kindly explain how whatever process you hypothesise caused God and all the raw materials of the Universe to exist, could not just as probably have caused a ready-created universe which did not require a God to exist?

Actually, I just realized that an animal cannot evolve; only populations can evolve. For instance, there were always some combination of small-legged and large-legged lizards in the cited example. However, what has changed was the distribution of those sub-characteristics within the overall population.

What really gets me is what 'behaviour' has to do with anything when there is simply an environmental change.

Note that I think this is distinct from evolution by mutation, which is the actual addition of ch

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Well, as I am the poster of this story and enjoy many things about evolution (book recommendation [amazon.com]), I'll give you the best answer I can though I am not an evolutionary biologist. First off, anything about evolution is controversial. Second, it's controversial because if these animals didn't become tree-born, this quick evolution of short legs never would have happened. A lot of evolutionary theory revolves around evolution not by choice (example of the brown moths becoming dominant over white moths during the industrial revolution when smoke and carbon on trees and buildings hid them). But this almost suggests that the decision to take to the trees is in and of itself a factor in evolution. So it appears that there is evolution by way of behavior in addition to random mutations. I guess what I'm saying is that a lot of people consider evolution to be purely random... but this study suggests that behavioral choices influence that.

Maybe you can argue that it was only natural for them to seek safety in the trees but I think that this study addresses something we must face. If you believe in evolution, you have to acknowledge that it's not only random genetics but also influenced by the behaviors of the animals granted those random mutations. If the lizards had behaved differently and not gone to the trees, perhaps longer and longer legs would have been developed until they were fast enough to outrun their predators. Or perhaps the species just would have been eradicated on the island.

Controversial because it implies that species may be able to subconsciously choose which feature is 'evolved' to be the dominant factor.

If you want to apply this to human evolution (as one is naturally only concerned with their own species), then I suggest you read Guns, Germs & Steel [pbs.org] by Jared Diamond. What I found interesting is that in some places, humans began a farming lifestyle earlier than other hunter-gatherers. It was this decision by way of discovery that led some civilizations to outpace others. In fact, the choice or 'discovery' of planting seeds and harvesting them periodically eventually led to some regions invading and 'colonizing' other regions. Can we call this evolution? Can we say that some evolution hinges on behavioral choices? I think we can, but that's why it's controversial because it has traditionally been thought that the dominant feature was only influenced by the environment--not by a choice made by the animal.

I think that people are reacting badly to this because you seemed to have thought the study was evidence of Lamarckian evolution, with the anoles actively giving themselves shorter legs. Reading the blurb, that's certainly what I thought you thought.

Presumably if this paper is going to be in Science, evolutionary biologists think there's something especially novel to it, but I'm with the people who think it's obvious enough.

Incidentally, I know it's contrary to the way things are done here but the best way

I'm not sure I agree with you about the possibility of any controvesy here. I, obviously, haven't read the article so I'm just responding to your comments here.

Firstly Evolution is not always controversial, a massively insignificant minority occasionally try to cast aspersions upon it but this doesn't make it controversial.

Secondly I don't see the choices made by the lizards to live in trees rather than remain on the ground and be eaten by predators is any different to the way I understood evolution to work in general. The way I see it in this case living in the trees is more likely to make you live long enough to breed than continuing to live on the ground, animals with shorter legs are better at climbing trees and more likely to be able to get up them in time rather than their long legged cousins who get eaten. Does the article suggest that those animals with long legs don't take to the trees for their survival or that they do but are just not good enough at tree climbing to escape successfully ?

Basically it looks to me like the physical attributes of the animal are determining who is evoloutionarily successful and its simply the pressure of the enviroment which is creating a shorter legged species which prefers to run up trees.

"Firstly Evolution is not always controversial, a massively insignificant minority occasionally try to cast aspersions upon it but this doesn't make it controversial."

He's not talking about Christian fundamentalists, he's talking about scientists, biologists, geneticists, etc. If you think that they are in lock-step agreement about evolution, and they never disagree or argue or have controversies, you've never been to an academic conference. Case in point: punctuated equilibrium.

I suspect they are largely arguing how to how the mechanics of evolution work rather than suggesting entirely seperate theories which take nothing from evolution at all. This is exactly the same as any scientific work so if you're saying that evolution is controversial then you must also be saying that all scientific theories are controversial.I would say that we expect their to be disagreement about scientific theories and this is in fact the default position to take so for a scientfic theory of any kind t

Again, case in point: punctuated equilibrium. Darwin's original theory claimed gradual change over time, and this was accepted up until the emergence of punctuated equilibrium. But when you look at the fossil record, there *isn't* gradual change over time. For most of the time, millions of years at a stretch, the morphology of species remain relatively *unchanged* -- until there is a periodic big explosion, for whatever reasons, of new morphologies.

Again, case in point: punctuated equilibrium. Darwin's original theory claimed gradual change over time, and this was accepted up until the emergence of punctuated equilibrium. But when you look at the fossil record, there *isn't* gradual change over time. For most of the time, millions of years at a stretch, the morphology of species remain relatively *unchanged* -- until there is a periodic big explosion, for whatever reasons, of new morphologies.

He's not talking about Christian fundamentalists, he's talking about scientists, biologists, geneticists, etc. If you think that they are in lock-step agreement about evolution, and they never disagree or argue or have controversies, you've never been to an academic conference. Case in point: punctuated equilibrium.

That is a relatively minor debate. There is no question that evolution happens or that it is due to natural selection.

I really don't think it works like that, anoles with shorter legs are better at climbing trees but they don't start developing shorter legs in order to climb trees. Instead because they are climbing trees this leads to an advantage ( not being eaten ) over their cousins who are not so good at climbing trees.

What you seem to be suggesting is that the anoles thought to themselves, "Hmm, we'd be better off with shorter legs, lets make our kids have shorter legs".

What it suggests to me is that the lizards with long legs did take to the trees and that their offspring and their offspring's offspring started developing shorter legs as they adapted to growing up climbing trees.

Which is, of course, completely inaccurate.

From TFA:"The change came sooner than expected. Just six months later the anoles were almost exclusively tree-dwelling, and longer-legged lizards had died in disproportionate numbers."

The average leg length in the population shifted because short legged a

A new predator was introduced, altering the environment in which the lizard operates. Suddenly running away is less effective than climbing trees, so lizards with the tools and inclination to climb trees survive at a better rate in the new environment. Perhaps a naive observer might read some "decision" on the part of the lizards into this, but it looks like pretty simple natural selection to me. The instincts and behavioural patterns of

No. Really, it's not. It;s directly observable - you can see this from the experiment.

Second, it's controversial because if these animals didn't become tree-born, this quick evolution of short legs never would have happened.

.

Nothing controversial about that. If peahens didn't prefer to mate with showy males as a measure of fitness, presumably we wouldn't have peacocks.

A lot of evolutionary theory revolves around evolution not by choice (example of the brown moths becoming dominant over white moths during the industrial revolution when smoke and carbon on trees and buildings hid them). But this almost suggests that the decision to take to the trees is in and of itself a factor in evolution. So it appears that there is evolution by way of behavior in addition to random mutations. I guess what I'm saying is that a lot of people consider evolution to be purely random... but this study suggests that behavioral choices influence that.

No. This almost suggests nothing of the kind. The lizards tried to escape by climbing. Those with shorter legs were better climbers and were therefore "fitter" the lizards didn't sit around stroking their chins and devising a cunning new survival strategy.

Maybe you can argue that it was only natural for them to seek safety in the trees

.

Precisely. This was clearly a behaviour used by the ancestral lizards when there were predators.

but I think that this study addresses something we must face. If you believe in evolution, you have to acknowledge that it's not only random genetics but also influenced by the behaviors of the animals granted those random mutations. If the lizards had behaved differently and not gone to the trees, perhaps longer and longer legs would have been developed until they were fast enough to outrun their predators. Or perhaps the species just would have been eradicated on the island.

Uh - yeh, OK. So what's the problem? No controversy there.

Controversial because it implies that species may be able to subconsciously choose which feature is 'evolved' to be the dominant factor.

What? That's just silly. Short legged lizards are better at climbing trees and survived It's as simple as that. Long legged ones could neither climb very well, nor run fast enough to escape. They were shit out of luck.

If you want to apply this to human evolution (as one is naturally only concerned with their own species), then I suggest you read Guns, Germs & Steel by Jared Diamond. What I found interesting is that in some places, humans began a farming lifestyle earlier than other hunter-gatherers. It was this decision by way of discovery that led some civilizations to outpace others. In fact, the choice or 'discovery' of planting seeds and harvesting them periodically eventually led to some regions invading and 'colonizing' other regions.

It's been a long time since I read it, but he makes a persuasive case that farming took off in certain regions because the natural wildlife were well adapted to being used as crops (large grain size etc.)

Can we call this evolution?

Nope. You can call it the predominance of a successful meme, if you want.

Can we say that some evolution hinges on behavioral choices? I think we can, but that's why it's controversial because it has traditionally been thought that the dominant feature was only influenced by the environment--not by a choice made by the animal.

You're seeing controversy where none exists. Really. Behaviour effects evolution and vice versa all the time and it has nothing to do with conscious decision. A classic case. In the UK hedgehog behaviour has changed dramatically over the last 40 years. They no longer curl up in a spikey ball when threatened by cars on roads - they run for it?

Evolution can be divided into two parts, adaption and speciation. Adaption is merely the process of physical changes to adjust to the environment. It isn't a theory as it has been observed many times (note the original article), and it should only be controversial to people who believe OJ is innocent. Speciation is when a new species arises from a different one. This is a theory, and I suppose it is highly controversial to some (many). *shrugs* But, the mere concept of adaption can't possibly be contr

I think the evidence here is delightful but your conclusions are way wrong.One: behaviour is determined by evolution. Not entirely, behaviour can also be transmitted by culture, and invented by animals showing creativity. But generally behaviour is the work of the genes: try reading the Extended Phenotype (Richard Dawkins) for an understanding of how this works.

Two: to describe the anoles as "subconciously choosing" their evolution is anthropomorphising the critters somewhat. It looks to me like you have 4

Controversial because it implies that species may be able to subconsciously choose which feature is 'evolved' to be the dominant factor.

No, it implies no such thing. Behavior is a genetically regulated trait, just like leg length. So some anoles have genes that make them spend more time in the trees, while others make them spend more time lower down. Selection by predation alters the proportion of the genes.

What is more interesting about the article is that the long-legged phenotype first increased, then d

Maybe you can argue that it was only natural for them to seek safety in the trees but I think that this study addresses something we must face.

No, because it IS only natural for them to seek safety in the trees. Or rather, all that needed to happen was for SOME to seek safety in the trees. There will be natural variability in the behaviour. What you are seeing is not behaviour influencing evolution, but the precise opposite - behaviour being selected by evolution. Without predators, tree-climbing would

There is no controversy around a link between behaviour and evolution. That's pretty mainstream in evolutionary biology.

You don't understand the study itself, either. It's a fairly standard example of rapid evolution: predator kills more long-legged anoles than short-legged anoles, therefore more short-legged anoles reproduce, subsequently the proportion of short-legged anoles in the population goes up, which is the definition of evolution. Sure, the reason the short-legged anoles are more successful has

That's not what they're suggesting. There are multiple layers of incorectness here, but the study itself seems interesting.The original poster is merely regurgitating the sentiment of the article, but they're both wrong about the "controversial" idea supported by the study.

All that the study suggests is that evolutionary changes can happen quickly when new selection pressures are applied, or, more importantly, when a group of thikning creatures takes a different approach to a problem (which may be a geneti

It's controversial because intelligence is not involved. The lizards appear to be growing longer or shorter legs based on what the situation around them is.
At a first glance, the article appears to reintroduce Lamarckism [wikipedia.org].

The research page itself however, offers a completely different explanation:
"This suggests that the results observed in the field may be the result of a phenotypic plasticity in limb growth, rather than genetic differentiation."
What they're saying isn't that the genes change, as the a

A good example of phentotypic plasticity is found in ants. The different castes of ants in a hill are very different, such as workers and guards. This difference isn't found in their genes. Their genomes contain the molds for all the variations.
The eggs are treated differently, and this results in vastly different creatures coming out of the egg.

This is what the study suggests is happening, to a lesser degree, in the lizards.

I think your comment is wildly inaccurate. The study is suggesting that the anole population is demonstrating rapid evolution of shorter leg lengths. Nowhere does it suggest that leg lengths are being influenced directly by environment, as if the act of climbing, or the presence of predators, lead to the legs of a particular individual being shorter. What it does suggest is that individuals with shorter legs get predated less often, and leave more short-legged offspring than their leggier relatives. That's

How many people on Slashdot have said that the gene pool has become watered down due to the protections of civilization?

In the past 200 years (10 generations by conventional reckoning) the human population of Earth has increased more than six-fold.

This huge increase in population has been accompanied by virtually no selective pressure. We know that because "selective pressure" is a nice polite way of saying, "loads of people dying." Evolution operates via differential survival of different bloodlines, and

In the Western world it can be argued that there hasn't been selection pressure for 50 years. I don't agree with that as I think that changes in our current society have been very stressful for people who aren't suited to it. Literacy is an example of something which is very important nowadays but wasn't as much in the past. People with learning difficulties find it harder to cope and anti-social aggression doesn't have the side benefits it once did.Previous to the last 50 years there have been massively hi

How many people on Slashdot have said that the gene pool has become watered down due to the protections of civilization?

"Watered down" has no real meaning. It is merely a sentiment that has no basis in facts. There is no way to "water down" a gene pool. You can't stop evolution by "protections of civilization." As long as individuals die and there is some differential in reproduction, evolution is happening. Sure, the evolutionary pressures and the source of mutations are changing slightly, but nothing is

This isn't evolutionary adaptation - it's much more simple than that. If you start killing all of the lizards with long legs, the ones with short legs are going to mate and have offspring with short legs. There is nothing new or "adapted." Also, if the short-legged ones get away and the long-legged ones don't, isn't that going to inherently affect how many have long legs and how many have short, by proportion?

This isn't evolutionary adaptation - it's much more simple than that. If you start killing all of the lizards with long legs, the ones with short legs are going to mate and have offspring with short legs.

No, it's saying the bahavior of climbing tress rather than running away led to differential selection for the tree climbers. Sort of like the way men who fell asleep after sex left more offspring than the ones who got up and left.

The author of the article has wildly misunderstood the study.
What the study is saying is: "This suggests that the results observed in the field may be the result of a phenotypic plasticity in limb growth, rather than genetic differentiation."

Phenotypic plasticity is something we find amongst other thing in ants.
The various castes of ants (workers, warriors, etc) differ from eachother quite a bit. However, their genes are the same - Their genome holds the molds for all their various forms. Through diff

Congratulations, you have succinctly described evolutionary adaptation - a population where some individuals breed more successfully than others due to naturally occurring variety. The mean length of leg of the population decreases and it appears as if the population has adapted to the new circumstances.

Both aspects are needed for evolution to occur: The variation through mutation etc., and the differential selection.

This isn't evolutionary adaptation - it's much more simple than that. If you start killing all of the lizards with long legs, the ones with short legs are going to mate and have offspring with short legs. There is nothing new or "adapted." Also, if the short-legged ones get away and the long-legged ones don't, isn't that going to inherently affect how many have long legs and how many have short, by proportion?

If you read the article, maybe you would wonder why the lizards didn't just keep growing longer l

If you read the article, maybe you would wonder why the lizards didn't just keep growing longer legs to outrun the predators.

With all due respect - only if you assiduously avoid thinking. Running away from a predator up a tree is is a strategy that can be implemented by an individual immediately. "Growing longer legs" is something that may happen to a population over many generations if there is both the selection pressure and the existing genetic diversity.

This isn't evolutionary adaptation - it's much more simple than that. If you start killing all of the lizards with long legs, the ones with short legs are going to mate and have offspring with short legs.

Yes it is. It that is exactly what evolution is, and how it works. While the adaptation may be small (and, to your mind, negligible) it is the gradual accumulation of millions upon millions of such small changes that results in all of the difference we see between extant species. If you keep up the pre

The whole article in National Geographic is terrible. It doesn't say anywhere what sort of evolution they're talking about.It does say "Losos and his colleagues' work reported only on changes in the anoles over a single generation". Let's say Stalin kills off all intellectuals in Russia, so that the only Russians left alive are non-intellectuals. Would this provide evidence for evolution in Russian society? Of course not! To see evolution, you need to see multiple generations of the thing that's evolving.

I think you read only the description and didn't bother to RTFA. The article is pretty interesting because it talks about 2 ways to adapt to changes:1. physically selection -- longer legs get selected2. behaviour selection -- those who climb in trees get selected (those good climber have shorter legs which is opposite to first way of "adapting")So, in this case, it seems that behavioral selection is more important than physical selection and that takes precedence and thus behavior influence the physical con

From the article description, I thought this experiment was going to provide evidence for Lamarkism [wikipedia.org] or something. In fact, this seems an interesting, but not too-surprising finding.

Introduce a change to the environment that causes a behavioural change - is it so surprising that some members of the population are better suited to the behaviour than others?

Apropos nothing, it's pretty sad to see such a story headed with the words "Pending your beliefs about evolution" on a site such as Slashdot. Evolution is an observable fact. Evolution through natural selection is a massively successful and well supported theory.

To the extent non-mathematical facts exist, Evolution is one. In the common parlance, we assume facts do exist. We consider those theories, (such as "the sun will rise tommorow") whose evidence passes an extremely high level of confidence, to be facts. Evolution is amongst these. We have gathered the evidence that makes us so sure about Evolution by making observations; others who make all those same observations should also be sure. Hence I feel it is entirely reasonable, and even desirable, to descri

"'Well, you have to draw the "fact" line somewhere... the poster I was replying to was sugesting neither observations, nor anything based on them should be considered facts.'No, he was noting correctly that actual evolution of humans hasn't been observed. I think that he missed (which I thought was part of your point) that all the aspects of evolution have been observed to some degree and hence are facts in themselves."

Both are reasonable interpretations of his original post, and I think yours is the more o

No doubt "behaviour influencing eveloution" will be seized upon by the intelligent design brigade. Though as usual the headline is misleading.
Instead of evolution on one axis (e.g. speed) it's on a combination of various abilities (running fast/hiding/climbing/fighting) plus choosing the right strategy. If the rules of the game change, e.g. a faster predator comes along, what you see is what you'd expect - those adapted for running away (as opposed to the hiders, the climbers, the smelly chemical squir

I'm in no shape or form a scientist, but is this really an example of evolution? The long legs vs. short legs reminds of the the hiking boots vs. running shoes joke. I think this is a better example of the I-don't-have-to-outrun-the-bear-just-you school of thought.

yes, and if you run an I-don't-have-to-outrun-the-bear-just-you experiment on a species for a couple generations, they will eventually evolve some mechanism for going faster and faster. Which is what "happened" here... except, partway into the beginning of the experiment, they realized that they didn't have to do any real outrunning, they just needed to climb a tree. So, naturally, the ones that were better at climbing trees survived and had more chilluns... thems chilluns had the same features as their bet

So by behavioral changes, is the author referring to Marcianism?
Because running up a tree is a poor example.
I'm not a biologist so please correct me if I'm wrong but I thought
"behavioral evolution" (which was dominant even after Darwin until about 1900)
says that as an animal lives its life, its behavior changes based on the environment
and those changes are then passed on to it's children. This would explain how
animals were able to adapt and evolve in the then-thought short history of the Earth.

This is a cool experiment, but it's nothing "new" -- there's no new knowledge here. At all.

AND there's NOTHING AT ALL about "behavior may be inherited!" Where did THAT come from -- anyone?(*) All these lizards were already prone to running up trees. The ones with shorter legs did it better, and within just a few generations the average legs length of the population was shorter.

That's *basic* evolution, people. Go read a damn book!!! The submitter of this article makes me angry because I realize now the fight for education about Evolution isn't just for stupid fundamentalists. A lot of smart people don't get it either.

I highly recommend getting yourself a copy of "The Selfish Gene" by Richard Dawkins. Read all the chapter notes, too -- get the recent version, don't gt an original copy because it makes you cool. Dawkins commentary on what he wrote in the newer printings is invaluable. It's an excellent book, and it's FUN to read... seriously!

(* I mean, in this context. It's well-known that behavior is inherited -- but not learned behavior.)

Both books show quite well how the modern synthesis is changing and what is likely to incorporated into it. The former book is particularly revolutionizing, the latter is every bit as readable as Dawkins is for the layperson. Both books benefit from the wealth of insigh

I read awhile back about comparing possum on an isolated island showed a much stronger genetic base that produced better litters and eventual adults versus those who lived on the mainland.

Apparently the stress put on possums on the mainland is high enough to cause genetic changes. the stress weakens the immune system and has other side effects that produced a less healthy and capable possum. One possibility that was raised is that on the mainland a good number of possum are killed by vehicles. Cars are obviously a predator that mainland possum can adapt to, or maybe there hasn't been enough time yet?

I wish I could find the exact story but all I end up with are references to NZ based studies.

The study supports the controversial idea that an animal's behavior in response to environmental change can spur evolutionary adaptations.

Pure random chance in conjunction with natural selection seems inadequate, by itself, to explain many of the, sometimes rapid, evolutionary changes that we see in nature. Some kind of feedback system whereby the useful traits of one generation are emphasised in succeeding generations (to a greater degree than pure genetic inheritance would suggest) could be the key miss

Of course useful (= survival/breeding advantage) traits are emphasized! That's the definition of useful in this context. Each generation has more "useful" traits than the preceding one simply because lack of those traits is what caused some members of the prior generation to die before breeding or to be less successful at breeding and therefore be disproportionatly underrepresented in the following generation. This is evolution 101.Depending on how dire the environmental change is that made previous accumul

Of course useful (= survival/breeding advantage) traits are emphasized! That's the definition of useful in this context. Each generation has more "useful" traits than the preceding one simply because lack of those traits is what caused some members of the prior generation to die before breeding or to be less successful at breeding and therefore be disproportionatly underrepresented in the following generation. This is evolution 101.

Yes, as I tried (inadequately) to explain, I am quite aware of the theory o

I'm not sure why you assume it must take many generations for a change to occur. Note that we're not talking about time for the genetics to change, but rather time for slowly preaccumulated genetic change have an effect based on a modified environment. In the extreme case where absence/presence of a genetic variation suddenly (due to environmental change) became a life or death issue, then you'd see the population genetics sharply change from one generation to the next.Note that when it comes to things like

I don't get what this has to do with behavior.The biggest influence on evolution is the environment (competetors, predators, food sources, climeate, etc). What seems to happen is that genetic variation slowly (by it's nature) builds in a population over time, then the environment occasionally quickly changes (the environment can change quicker than genetics can) thus suddenly making some previously begign genetic changes beneficial and others detrimental. I believe this is the basis for the "theory" (i.e. o

"Epigenetics is the study of epigenetic inheritance, a set of reversible heritable changes in gene function or other cell phenotype that occur without a change in DNA sequence (genotype). These changes may be induced spontaneously, in response to environmental factors, or in response to the presence of a particular allele, even if it is absent from subsequent generations."

at least as far as the evolution being affected by animal behavior. The behavior can change the environment, and hence the selective process, nothing new or surprising there. Now if it said that behavior directly caused the change (i.e. created mutations), I'd say that's controversial, but I find this is nothing especially exciting, even if it did get into science.

This is exactly how I thought that evolution was supposed to work. Environment changes due to new predator, species evolves to handle changed environment. Yet another routine confirmation of Darwin.

How are longer legs "behaviour"? Not that I would be surprised that behaviour has Darwinian consequences. The behaviour of reproductive mating has considerable consequences - species that stop reproducing lose the evolutionary challenge.

I've been saying for years that the "random mutation" model is not sufficient to explain observed reality. To me it's self-evident that what organisms do, or try to do, or possibly even want to do, has an effect on the mutations that occur (before natural selection plays its part), and natural history cannot otherwise be reasonably explained. However, this theory would mean that we're 99% ignorant of the mechanism of evolution, and modern science strongly prefers irrational but seemingly complete solution

Long legs meant to escape were useless against the new larger predators while short legs became the dominant feature since they increased climbing ability (to trees the predators could not reach).

This could simply be the animals with long legs being eaten at a more frequent rate, so the short legged lizards are the ones surviving and reproducing. This is, at best, micro-evolution. Their genetic makeup isn't changing to accomidate the need for short legs (like evolution would *know* that it needed short legs). Its selective breeding.

What a bunch of claptrap! You apparently know NOTHING about natural selection. I'd be very surprised to find that Carl Sagan did indeed present such a preposterous notion. Carl Sagan was a respected scientist whereas you are...? Thought so. Go lay your pseudoscience turds on an audience that cares. Digg.com perhaps?

Man. Someone forgot to take his happy pill this morning I see. Look, I'm only repeating what I saw on a legitimate science show. I didn't make this stuff up. Go look it up! The main article being featured on Slashdot goes a long way to explaining why the sheep would change colors when exposed to stimuli like those poles. Until I read it, the fact that it happened remained a mystery and Carl Sagan didn't explain it too much other than to sy that it was natural selection at work. The only possible expl

Actually, at first, the longer-legged lizards were better survivors because they're faster runners. For the first six months of the experiment, they had an advantage.When the anoles learned that they could better avoid the predator lizards by climbing trees, the shorter-legged lizards had a climbing advantage, and they were being selected for.

The summary only tells half of the story. The article spells it out completely. It was a behavior change on the part of the prey that caused a change in which trait

Perhaps the long legged lizards was an evolutionary dead-end once the predators were introduced.On introduction of the predators some lizards climbed to escape and some ran. For a while the longest legged run-away lizards survived as the predators ate the slower ones first. Why chase after the quickest ones when you can eat all the slow ones first.

As the slower ones were all eaten then the longer legged ones were caught as well and eaten. Now if the predators were slightly slower or the longer legged run-aw